Yes! That is what I should be doing. I had it setup to do exactly that, when suddenly Zhifubao disabled my account and required me to provide bank details to prove that I am the account owner. This totally came out of the blue and I don’t know that I did anything to prompt it. I printed out my online account statement and uploaded it several times but they have refused to reinstate my account so far, even though there’s still 600 yuan in my Zhifubao account which I haven’t been able to access in the interim. So the last month or two I’ve been paying for taobao items using online banking (rather than Zhifubao which is much faster and easier).
You’re right though, the iPhone app which has Zhifubao built in is the fastest way to pay for items on taobao, it literally takes seconds.